This invention is in the field of sensor systems and particularly in the area of improved clutter rejection techniques.
The prior art for rejecting stationary clutter was the automatic clutter mapper described in U.S. Pat. No. 3,720,942. This automatic clutter mapper gave good clutter rejection performance for stationary clutter which occurred in a given automatic clutter mapper cell more than 25% of the time. Clutter was detected by incrementing an up-down counter by 4 with a detection, by one with a miss until a sufficiently large number of detections had been counted that the probability was very low that they could have occurred due to a moving target. At the time clutter was indicated, the clutter amplitude was measured and a threshold was set to reject the clutter.
Although foregoing stated technique worked well for rejecting clutter in a normal radar propagation environment, it allowed several times the specified clutter false alarm rate in a severe ducting environment (when radar propagation is not straight line but trapped by unusual atmospheric conditions).